356  
FXUS65 KBYZ 210256  
AFDBYZ  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE BILLINGS MT  
856 PM MDT SAT JUL 20 2019  
   
UPDATE
 
 
MADE ONLY MINOR ADJUSTMENTS TO THE FORECAST THIS EVENING TO  
ACCOUNT FOR CURRENT TRENDS. OTHERWISE, THE REST OF THE FORECAST  
REMAINS ON TRACK AND THE PREVIOUS FORECAST DISCUSSION AND AN  
UPDATED AVIATION DISCUSSION ARE BELOW. STP  
 

 
   
SHORT TERM...VALID FOR SUN AND MON
 
 
A VERY PLEASANT AFTERNOON ACROSS THE REGION WITH SUNNY SKIES AND  
TEMPERATURES MAINLY IN THE 70S. THERE IS A DISTURBANCE MOVING  
TOWARD THE AREA FROM THE NORTHWEST THAT WILL ARRIVE OVERNIGHT INTO  
TOMORROW MORNING. AS THIS SYSTEM APPROACHES, IT WILL PULL A VERY  
MOIST AIRMASS NORTHWARD INTO THE EASTERN HALF OF THE FORECAST AREA  
(BILLINGS TO THE EAST). PRECIPITABLE WATER VALUES WILL JUMP WELL  
ABOVE AN INCH OVER THESE AREAS AND PROVIDE ENERGY FOR SHOWERS AND  
THUNDERSTORMS FROM LATE EVENING INTO THE DAY SUNDAY AS THE  
DISTURBANCE CURRENTLY NORTHWEST OF THE AREA MOVES THROUGH. BEST  
CHANCES FOR SHOWERS AND THUNDERSTORMS TONIGHT WILL BE EAST OF  
HARDIN AND SOUTH OF A FORSYTH TO BAKER LINE. WITH THE HIGH  
MOISTURE CONTENT OF THE ATMOSPHERE TONIGHT, LOCALLY HEAVY RAINFALL  
WILL BE POSSIBLE. AT THIS POINT ORGANIZED SEVERE STORMS SEEM VERY  
UNLIKELY, BUT AN ISOLATED STRONG STORM WITH WIND GUSTS TO 50 MPH  
AND SMALL HAIL CAN'T BE RULED OUT.  
 
COOLER AND DRIER AIR BUILDS IN BEHIND THE DISTURBANCES TOMORROW  
MORNING. THE BEST CHANCE FOR PRECIPITATION WILL BE DURING THE  
MORNING HOURS OVER SE MONTANA, DIMINISHING AS THE DRY AIR BUILDS  
IN DURING THE AFTERNOON. AFTERNOON TEMPERATURES WILL BE VERY  
SIMILAR TO THIS AFTERNOON WITH 75 TO 85 DEGREES ACROSS THE  
REGION.  
 
AMPLIFIED RIDGE BUILDS INTO THE AREA ON MONDAY BOOSTING  
TEMPERATURES INTO THE UPPER 80S AND LOWER 90S FOR ALL BUT THE FAR  
EASTERN PORTION OF SE MONTANA. MOISTURE WILL STILL BE AVAILABLE  
UNDER THE RIDGE FOR SCATTERED AFTERNOON/EVENING MOUNTAIN BASED  
THUNDERSTORMS, BUT THESE STORMS WILL STRUGGLE TO PUSH VERY FAR  
OFF THE MOUNTAINS AS DRY LOW LEVEL AIR COMBINES WITH INCREASING  
MID LEVEL TEMPERATURES TO CAP CONVECTIVE POTENTIAL OVER THE  
PLAINS. CHAMBERS  
   
LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT
 
 
FEW CHANGES WERE MADE TO THE EXTENDED FORECAST. ENSEMBLES  
TREND TOWARDS THE CONTINUATION OF A RIDGE THROUGH WEDNESDAY FOR  
MONTANA. SHORTWAVES WILL PASS OVER THE AREA COMBINING WITH THE  
INSTABILITY ALREADY IN THE ATMOSPHERE WHICH WILL ALLOW AFTERNOON  
THUNDERSTORMS TO FORM ALONG THE FOOTHILLS AND HIGHER TERRAIN. THE  
RIDGE BEGINS TO BREAK DOWN WEDNESDAY NIGHT WITH THE PASSING OF LOW  
PRESSURE FROM ALBERTA INTO SOUTH EASTERN SASKATCHEWAN. ENSEMBLES  
SPREAD BEGINS TO INCREASE WEDNESDAY NIGHT INTO THURSDAY ON HOW  
DEEP THE TROUGH IS GOING TO DIG SOUTH. SOME OF THE MEMBERS WANT TO  
DROP THE HIGH TEMP BELOW NORMAL WHILE OTHERS WILL KEEP IT ABOVE  
NORMAL. HIGH TEMPERATURES TUESDAY AND WEDNESDAY WILL REACH THE LOW  
TO MID 90S BEFORE DROPPING SLIGHTLY WITH HIGHS REACHING THE MID  
TO UPPER 80S. LOWS WILL REMAIN IN THE 50S AND 60S. CARROTHERS  
 

 
   
AVIATION
 
 
IN GENERAL, VFR CONDITIONS WILL PREVAIL OVERNIGHT. HOWEVER, A  
DISTURBANCE MOVING THROUGH THE REGION WILL CAUSE SCATTERED SHOWERS  
AND THUNDERSTORMS TO DEVELOP OVER SOUTHEAST MONTANA TONIGHT,  
CONTINUING INTO SUNDAY. THE STRONGER THUNDERSTORMS HAVE A  
POTENTIAL FOR GUSTY AND ERRATIC WINDS, HAIL, AND HEAVY RAINFALL.  
THESE STORMS HAVE A POTENTIAL FOR MVFR TO IFR CONDITIONS. STP  
 

 
   
PRELIMINARY POINT TEMP/POPS
 
 
SUN MON TUE WED THU FRI SAT  
-----------------------------------------------------------  
BIL 056/083 058/092 064/095 066/096 064/089 062/088 060/088  
10/U 00/U 11/U 11/B 11/U 11/U 11/B  
LVM 046/081 051/089 057/092 058/091 056/087 054/086 053/086  
10/U 01/U 22/T 32/T 31/U 11/U 11/U  
HDN 057/081 057/090 062/094 065/094 063/088 061/086 059/087  
20/U 00/U 11/U 11/B 21/U 10/U 10/U  
MLS 057/081 056/087 062/093 065/094 065/088 062/086 059/087  
21/U 00/U 00/U 10/B 20/U 10/U 10/U  
4BQ 057/078 055/084 060/091 064/092 063/087 061/086 058/085  
52/T 00/U 01/U 11/B 21/U 11/U 11/U  
BHK 055/078 054/082 059/088 061/089 063/086 059/083 057/083  
32/T 00/U 00/U 01/B 21/U 11/U 11/U  
SHR 055/079 054/089 059/093 061/092 060/087 058/086 056/086  
21/B 12/T 22/T 32/T 33/T 32/T 22/T  
 

 
   
BYZ WATCHES/WARNINGS/ADVISORIES
 
 
MT...NONE.  
WY...NONE.  
 

 
 

 
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